The present invention relates to a circuit board with a cooling device having channels through which a cooling agent flows.
Dissipation per unit area or unit volume increases with increasing component density in semiconductor integrated circuits. The heat produced must be effectively removed by being transferred, for example, through the leads or via the contact area of the component to the circuit board, distributed on the latter and carried away. The heat removal must be fast enough to prevent the formation of overheated spots, which, in the worst case, may result in a failure of the semiconductor components. In the case of circuit boards with high component density, i.e., circuits in which much heat is generated, such a distribution and removal of the heat produced is no longer sufficient, so such circuit boards must be provided with an additional cooling device.
A prior-art cooling device described in European Patent Application No. 0,083,538-B1 consists of a hollow copper plate provided with internal partitions which form the cooling channels. Bonded to one or both surfaces of the hollow copper plate is a circuit board to which the semiconductor components are soldered either directly or via leads.
To form the hollow copper plate, a model of wax or any other low-melting material is produced in which the copper partitions are embedded or holes are made for passing the leads therethrough. The entire surface of the model is then coated with copper by an electrolytic process. The copper coating is subsequently removed at two lateral opposed faces by machining. Finally, the wax or the like is removed by dissolution, thus leaving hollow spaces serving as cooling channels. The production of the hollow copper plates is thus very complicated and costly and no especially suited for volume production.